The OP says he has a friend who misses the days of UO for its "things like housing, thieving and looting." It was all a part of a game (and correct me on this, since I don't know from first-hand experience) with a very loosely designed structure and an open view of dealing with player interactions. But many of the people who replied to the thread didn't have nice things to say about this system. Rather, the open system allowed the game to be ruined by its worst elements. Near the end of the game's lifespan, it was centered around a sense of fear of other players, the constant notion of losing hours or days of work from one gank by an experienced griefer.

One commenter discussed this as a theory of wolves and sheep. In an ecosystem, if you have the same number of wolves as you do sheep, then wolves will start to die out. You need a lot of sheep for the wolves to eat if they want to consistently have enough food. But if a flock of sheep are constantly getting attacked, then the sheep will all leave the dangerous area, and the wolves will have nothing to eat.

And that's what happened with UO. When the game first came out, it was really the only thing of its caliber that was around. This meant that if your goal as a gamer was to run around killing other people in unfair fights, you had plenty of targets. The game attracted a lot of "wolves" who recognized a lot of easy prey, and thus just wandering from town to town became nearly unbearable. The loss of everything on your person for a kill made the situation not just annoying but made your entire game counter-productive.

So unsurprisingly, Everquest comes out, and people switch in droves. The game is said to have a better PvP environment, even though there are technically more restrictions on the PvP environment. The sheep end up leaving the pasture. So what do the wolves do? There's not enough people left to gank, and heaven forbid the gankers go try to hunt each other. So many of them cry about what a bunch of carebears people are and end up leaving the game. It leads to this sense of entitlement that people are supposed to just hang around and be easy prey - how dare people want to leave to go play a game where they can walk around in town without fearing of losing half their stuff!

It gets into an interesting demand for PvP. You want to give people the ability to play assassin-style characters, but you also have to set up a system by which people are willing to be assassinated. A lot of people suggest EVE as a spiritual successor to UO, which has that sort of open PvP, where a sudden pirate raid can mean the loss of a lot of your goods, but EVE also has a high-defense space where pirating gets you in more trouble with NPCs, and there's much greater emphasis on joining a corp so that you're not just wandering around undefended. But EVE still suffers from some recruitment problems - deserved or not, the image that it projects to people who haven't played it is as a difficult game to crack into without massive amounts of time and also money to buy a character who's already a year old.

Aside from EVE, the idea of full world PvP is eroding in other MMORPGs. WoW made attempts to revive open world PvP with recent expansions, but as one commenter mentioned, why would you call people up, wait half an hour to get enough friends together to hold a tower, only to be swarmed by people with higher levels than you who show up for the gank everyone - when you could just log into a battleground and fight people on roughly equal terms? Which is to say nothing of games with no PvP... or of the very low-risk MMOs now being pushed on facebook.

So yeah, it's worth taking a read through the comments. It's an interesting take on the whole "carebear" culture, wherein people are constantly whining on forums about how people don't really play MMOs these days, how MMO players aren't as hardcore as they used to be or cater to the casual crowd too much, when the number of people who could actually be hardcore in these games was limited, and a lot of the others were forced to play the victim.

I myself have always approached PVP (in regard to MMOs, at least) in a matter-of-fact way; if I play on a PVP server, I PVP when I get the opportunity. If I see an enemy and I think I can take them, I go for it.

That said, I know I've personally passed up an opportunity to destroy a low level character; there's no challenge involved and you're just ruining someone's day. That's why I tend to favor non-linear growth in games; if there aren't any statistical bonuses, then everyone is the same 'level' and has the same footing.

'Realistic' player interactions like those in UO are pretty much dead at this point. A player who loses everything because another player stomped them, stole their keys, took their house, girlfriend and dog is probably never going to come back. That's one less subscriber, so from a business standpoint it's a disservice. Free to Play games might be a different story, but you'd have to target a pretty narrow audience (people who are dumb/emotional enough to spend real money to try and get revenge).

I missed out on UO, but it sounds like I would have had a blast. Not as a wolf, or a sheep, but as a member of a community that is populated by both. Whereas the MMOs I've played are generally populated by morons.